Category Archives: Relativity

Q: Is the Alcubierre warp drive really possible? How close are we to actually building one and going faster than light?

The original question was: Is this f’real? Astronomer: The Alcubierre spacetime metric is named after a Miguel Alcubierre, a physicist who was also a Star Trek fan. It describes a type of bubble in space, where you could put, for … Continue reading

Posted in -- By the Physicist, -- Guest Author, Physics, Relativity | 59 Comments

Q: Is it possible to experience different rates of time? If time were to speed up, slow down, or stop, what would you experience?

Physicist: It depends a little on how you define “experience”, but in general you’ll always experience time moving in exactly the same way.  So sci-fi movies where the characters are experiencing slowed-down or sped-up time and are having a hard … Continue reading

Posted in -- By the Physicist, Philosophical, Physics, Relativity | 18 Comments

Q: How does instantaneous communication violate causality?

Physicist: You may have heard that if a technique can be found that allows you to send a signal faster than light, then you can send a signal back in time.  The very short answer for why is that relativity … Continue reading

Posted in -- By the Physicist, Physics, Relativity | 37 Comments

Q: Can you poke something that’s far away with a stick faster than it would take light to get there?

The original question was: If I had a really long (about 500,000 km) and really stiff stick would I be able to send information faster than light by moving it quickly by 1 cm and poking someone on the other … Continue reading

Posted in -- By the Physicist, Physics, Relativity | 17 Comments

Q: Satellites experience less time because they’re moving fast, but more time because they’re so high. Is there an orbit where the effects cancel out? Is that useful?

The original question was: I read that due to time dilation from both gravity and speed, GPS satellites need their clocks adjusted to match Earth’s time or else the whole idea would fall flat on its face. So my question … Continue reading

Posted in -- By the Physicist, Physics, Relativity | 11 Comments

Q: Do time and distance exist in a completely empty universe?

Physicist: This is a classic philosophical question! For a while, it was generally assumed that without matter distance and time would still exist.  After all: why not?  Time is time and space is space, and the material things in them … Continue reading

Posted in -- By the Physicist, Philosophical, Relativity | 25 Comments